Computer systems that build virtual machines (VM) that use the resources of physical machines (PM) and carry out business processing using the VMs are known. An example of a PM is a physical computer, and an example of a VM is a virtual computer.
A VM load balance technique using a genetic algorithm is disclosed in Patent Literature 1 as a technique related to this kind of computer system. Specifically, in the technique of Patent Literature 1, a resource threshold is provided in the PM. The resource threshold is the usage threshold for a resource (for example, a CPU or memory). When PM resource usage exceeds the resource threshold during VM operation, a VM arrangement is computed such that the PM resource usage becomes equal to or less than the resource threshold, and VM migration is performed in order to realize the computed VM arrangement. This makes it possible to avoid the occurrence of a PM performance failure during VM operation.